"uncle arnie" wrote in message
...
On Thu, 30 Dec 2004 21:26, tianli posted to
rec.radio.shortwave: %MM


0.558 miles.

About 900 meters.

Is that in empty space or in an atmosphere?

speed of light or electricity is constant, never varies.

Sorry, Uncle Arnie, but you're way off on this one. The question was right
on. The value that you so often hear given for the speed of light is its
speed in a vacuum, which is constant barring other factors (i.e. massive
bodies.)

Here's a link explaining the experiment 5 or so years ago in which
scientists slowed it down to a mere 38 miles an hour.

http://www.news.harvard.edu/gazette/....18/light.html

"Light, which normally travels the 240,000 miles from the Moon to Earth in
less than two seconds, has been slowed to the speed of a minivan in
rush-hour traffic -- 38 miles an hour."

And to prevent anyone (and I don't mean you, Uncle) from claiming that
doesn't apply because it was due to human action or interference here's
another one:

http://cbc.ca/cgi-bin/templates/view...eedlight000720

"Light travels slower in any medium more dense than a vacuum, which has no
density at all. For example, light travelling through glass slows to
two-thirds its speed in a vacuum. If the glass is altered, the light can be
slowed even further."

I used that Canadian link on purpose, by the way. gbg